Systems for construction of formwork are known hereto and an earlier known example is disclosed in WO2011/138573 (SIFTEK). The earlier patent application shows a system having structural panels connected by connectors to define a cavity therebetween for receiving a settable compound such as concrete.
German Patent Application DE-A-19904431 (Schuller) describes an adjustable length spacer with a scissor arrangement.
Other prior art is disclosed in U.S. Pat. No. 4,765,109 (Boeshart) which shows an adjustable tie includes a pair of straps selectively connected together to form a single tie. Each of the pair of straps has a pair of spaced-apart plates at the outer end which will hold the panel of a wall form therebetween. Slots cut in the panels allow the tie ends to be inserted in the panels. The pair of straps which form each tie are identical, and have a series of pegs and apertures which are cooperable in selected positions to vary the length of the tie. In a second embodiment, the portion of each strap between the inner and outer plates is comprised of two interconnecting pieces so that the distance between the plates is adjustable, to allow for various panel thicknesses.
German Utility Model DE-U1-29618158 (Rausch) discloses telescoping pieces for use in a formwork.
U.S. Pat. No. 6,321,498 (Trovato) discloses a formwork for building walls comprising: a first facing panel and a first insulating layer and a plurality of parallel spacing members disposed therebetween. The parallel spacing members cooperate with a first facing layer and the first insulating layer to form horizontal and vertical channels in communication with each other between the first facing layer and the first insulating layer. A second facing panel has a similar structure. The first and second facing panels define a space therebetween and braces remain in situ when a cementitious material is poured in the space and solidifies.
Other examples of formwork construction systems are disclosed in Japanese Patent Application JP-A-2006112090 (Saihara Tadashi) and International Patent Application number WO-A-01/59227 (Polyform AGP Inc).
A problem which has existed was that associated with the storage and transportation of these formworks prior to deployment at a building site. Due to their nature a large percentage of the volume has been occupied by a space between the panels and this resulted in costly transportation.
The present invention arose in order to provide a formwork which could be stored in a compact form, for example transportation, and transformed quickly and easily, in a safe a reliable manner, to an open form when required and prior to assembly.
Another object of the invention was to provide a formwork that can be deployed into one of several different inter-panel spacing sizes for use in different applications and without the need to fabricate several different sizes.